Which of these is the 'Law of Syllogism'?
P ⟹ Q,P⊢QP \implies Q, P \vdash QP⟹Q,P⊢Q
P ⟹ Q,Q ⟹ R⊢P ⟹ RP \implies Q, Q \implies R \vdash P \implies RP⟹Q,Q⟹R⊢P⟹R
P∨Q,¬P⊢QP \lor Q, \neg P \vdash QP∨Q,¬P⊢Q
P ⟹ Q,¬Q⊢¬PP \implies Q, \neg Q \vdash \neg PP⟹Q,¬Q⊢¬P